Process for the production of mercurized printing plates



Feb. 27, 1934. H. e. ZIMMERMANN 1,949,233

PROCESS FOR THE PRODUCTION OF MERCURIZED PRINTING PLATES .Filed D80- 10, 1931 Hermanneeargzzlmmermann 1N VENTQ in Minna y. Y

Patented Feb. 27, 1934 PATENT OFFICE PROCESS FOR THE PRODUCTION OF MER- CURIZED PRINTING PLATES Hermann George Zimmermann, Bentleigh, Victoria, Australia Application December 10, 1931, Serial No. 580,216 In Australia July 27, 1931 2 Claims. .(Cl. 41-415) This invention relates to the production of printing plates having mercurized ink-repelling areas and it has been specially devised in order to provide printing plates having mercurized ink repelling areas which are durable and easily maintained in effective condition.

Printing plates according to this invention have the advantages but not the disadvantages of ordinary line and half tone printing plates and planographic printing 1 plates which have mercurized ink repelling areas. The improved plates can be used with great efiiciency on ordinary flat bed and rotary types of printing machines without increase of pressure. This advantage as such might cause damage or shorten the life of the machine.

According to this invention metal which is amalgamable with mercury is coated with a metal which is not amalgamable with mercury and the work is formed on the coating in known manner. The plate is then etched with a fluid which is adapted to attack the coating and also the metal below it. Etching is continued until all the parts of the coating which are not protected by work are removed and at will etching may be continued to a desired depth into the bare metal. The parts of the amalgamable metal exposed 'by the etchingare then amalgamated and the amalgamated surface is treated with a suitable fluid, such as a weak solution of nitrate of silver and nitric acid, such a weak solution of nitrate of silver and nitric acid producing a layer of mercury-silver amalgam having a matt surface which is then treated with metallic mercury.

To enable the invention to be more clearly understood the productionfof a printing plate suitable for commercial use will now be described with the aid of the accompanying drawing in which: Fig. 1 is a substantially sectional view of a plate comprising a layer of amalgamable metal provided with a coating of non-amalgamable metal. Fig. 2 is a sectional view of the plate with work deposited on the coating. Fig. 3 is a sectional view of the plate in Fig. 2 after the metal between the work has been etched away. Fig. 4 is a sectional view of a portion of the plate in Fig. 3 on a larger scale after the exposed face of the lower layer has been mercurized. Fig. 5 is also a sectional view of a portion of the plate in Fig. 4 after treatment of the mercurized face to produce a layer of mercury silver amalgam having a matt surface. Fig. 6 shows part of a completed plate. A base 7 of suitable amalgamable metal such as copper is coated as at 8 with non-amalgamable metal such as nickel.

coating may in some cases be only four tenthousandths of an inch in thickness but if increased durability is desired, the thickness may be increasedlto three or four thousandths of an inch. The work 9 is then formed on the coating in known manner with the aid of suitable material such as bichromated fish glue, after which the unprotected parts of the coating are etched away, as at 10, with a fluid adapted to attack .the coating and the base, for example perchloride of iron. Etching is carried out in manner well known to process engravers and the etcher is enabled to make full use of his skill to produce a satisfactory plate, stopping the etching in some parts, carrying it deeper in others, and so on, but in all cases the etch must be sufilciently deep to ensure that the parts carrying the work will be in relief after the surfaces of the base 7 have been amalgamated. After etching the plate is washed and is treated with an amalgamating solution containing, for example, ten ounces of a saturated solution of mercurous nitrate and water and one ounce of nitric acid, until the surfaces exposed by the etching are covered with a film of mercury as 11 after which they are rubbed with metallic mercury. The plate is now treated with a solution containing from five to ten grains of nitrate of silver to the ounce and one twentieth part of an ounce of nitric acid to the ounce, until a layer 12 of mercury-silver amalgam having a matt surface 12 is obtained. The plate is again thoroughly washed and the matt surface 12 is then rubbed with metallic mercury to produce a highly amalgamated face 13. The produced mercurized face will resist removal of the mercury during printing and is much more durable than a surface which has not been treated with nitrate of silver and nitric acid solution as described. Printing plates made as described will readily attract to their treated surfaces mercury supplied during printing to compensate for mercury removed from the surfaces. Mercury may be added to the ink or be sprayed on to the printing machine rollers in a. fine state of subdivision, only a small quantity being required to maintain plate surfaces in effective ink repelling condition. Plates made according to this invention, even after non-use for a considerable time, retain their aflinity for mercury and when again rubbed with metallic mercury are immediately ready for use. I

Although I have described this invention as applied to a plate having a lower layer of a metal amalgamable with mercury it is to be understood that other metals are usable if they are first provided with a sufliciently thick coating of a metal amalgamable with mercury but such coating must be firmly adherent to the base.

I claim: 1. Process for the production of printing plates having mercurized ink repelling areas consisting in coating a base of a metal amalgamable with mercury with a metal not amalgamable with mercury, forming the design on the said coating, amalgamating the exposed parts of the'base with metallic mercury, treating the amalgamated parts with a solution of nitrate of silver andnitric acid to produce a layer of mercury having a matt surface and applying metallic mercury to the surface thus produced. 

